The Spirits' Book
Book Two - The Spirit World
Chapter XI - The Three Kingdoms
Animals and Humans
596. How do some animals have the ability to imitate human speech, and why is this ability found in birds rather than apes, whose physical makeup more closely resembles that of human beings?
“That ability results from a particular development of the vocal organs, further supported by the instinct of imitation. Apes imitate the gestures of human beings, while some birds imitate their voices.”